Distribution Of Hydroids Research Articles

Depth‐ and substrate‐related patterns of species richness and distribution of hydroids (Cnidaria, Hydrozoa) in Arctic coastal waters (Svalbard)

AbstractHydroid diversity and species composition were studied in Arctic coastal waters around the Norwegian Svalbard Archipelago. The aim of the present study was to examine the influence of physical factors (depth and substrate type) on the distribution and diversity of the benthic hydrozoan fauna that has been poorly studied in the high‐latitude polar region. The study is based on a total of 557 samples collected between 1996 and 2007. Over 1200 colonies and 70 taxa of Hydrozoa were collected by SCUBA divers, dredges and van Veen grabs. The distribution patterns with respect to major environmental factors were studied based on presence/absence data. Four substrate types were most commonly colonized by hydroid colonies: algae, bryozoans, rocks and hydrozoans. The highest species richness was noted on algae and rocks. Shallow water communities of the study area were characterized by a high hydroid species richness. A number of species decrease along the depth gradient. Some species have shown some preferences towards selected substrates or one of the two depth zones, but most hydroid species were generalists in terms of both the depth and substrate preferences. No species could be classified as substrate‐specific (i.e. occurring only on one substrate type). The substrate heterogeneity was shown to be an important driver of hydroid species richness in Arctic coastal waters.

First record of the hydroid Eudendrium carneum (Cnidaria: Hydrozoa: Hydroidolina) in Indian waters

Work on hydroids from India is scanty, and the distribution of hydroids in India is therefore largely unknown. Thornely (1916) recorded 17 species of hydroids from Gujarat State. Mammen (1963, 1965a, b) contributed taxonomic information on almost 126 species of hydroids from southern India. Venugopalan & Wagh (1986) carried out work on benthic hydroids with ten records from the Maharashtra coast. Among hydroids, the widespread genus Eudendrium in particular is infrequently reported from India. Mammen (1963) reported Eudendrium capillare Alder, 1856 from southern India, the only known record of this genus from India. Eudendrium carneum Clarke, 1882 is a new species record in Indian waters from Poshitra, Gujarat. The present record thus assumes significance.

Hydrozoan diversity on hard bottom in Kongsfjorden, Svalbard

Hydroids in Kongsfjorden, Svalbard, were studied on five hard-bottom transects along gradients of environmental conditions from the glacier at the fjord's head to the fjord's mouth at depth-range 0–30 m. Hydrozoa colonies are widely distributed on rock and gravel substrata in Kongsfjorden. In general, however, hydroids are not dominant or subdominant in zoobenthic communities. The exception isSymplectoscyphus tricuspidatusvar.acuminatus, colonies of which were sometimes abundant enough to determine the community structure and characteristics of benthic diversity. Of the 23 species recorded in this study,Laomedea flexuosa,Phialella quadrataandHalecium tenellumas well as representatives of family Stylasteridae were recorded from Svalbard waters for the first time. Hydroid diversity was highest in the zoobenthic community structured by branched bryozoans. The abundance and distribution of hydroids were reduced, to some extent, in the inner part of the fjord compared to the outer fjord. Species richness of hydroids was high at shallow depths, decreased at around 15 m and then increased again to 30 m depth. Species with Low-boreal–Arctic and Panoceanic distributional ranges were the most frequently occurring species. Depth, type of background substratum and amount of silt on its surface were the main factors influencing hydroid distribution. Description of all recorded taxa distributions together with data on their habitat and associations in zoobenthic communities are presented in an Appendix.

Vertical distribution of hydroids in wharf fouling in the Northwestern Sea of Japan

The features of the vertical distribution of hydroids on various types of wharves in the northwest part of the Sea of Japan were studied. It was shown that the highest values of biomass of the common species of hydroids Obelia longissima and Bougainvillia ramosa were at wharf sites below the zone of varying submergence up to a depth of 1 m. The spatial variability of hydroid abundance is discussed in relation to the local specifics of their environment and the character of formation and the structure of the fouling community.

Abundance and distribution of hydroids in a mangrove ecosystem at Twin Cays, Belize, Central America

Abundance and distribution of hydroids in a mangrove ecosystem at Twin Cays, Belize, Central America