Habitat preferences of juvenile Tanner and red king crabs: Substrate and crude oil

Habitat preferences of juvenile Tanner and red king crabs: Substrate and crude oil

A. Moles and R.P. Stone

Habitat preferences of juvenile Tanner and red king crabs: Substrate and crude oilThis is part of Crabs in Cold Water Regions: Biology, Management, and Economics
PDF    
To download the free PDF [226.3 KB], please enter:
-or-

Description

Behavioral preference tests were used to determine whether sediment selection played a role in habitat choice in juvenile red king crab (Paralithodes camtschaticus) and Tanner crab (Chionoecetes bairdi) and how oil pollution might alter sediment preferences. In the absence of oil, 2-year-old juvenile red king crabs preferred a bryozoan-hydroid assemblage or cobble over shale, shell hash, sand, or mud. Sand was chosen <3% of the time and mud was never selected. Juvenile Tanner crabs selected bryozoan-hydroid assemblages or buried in either sand or mud and avoided the larger-grain substrates. In oil experiments using three sediment types (mud, sand,cobble), grain size was often more important in sediment selection than the presence or absence of contaminants. If the preferred sediment type was oiled and the alternative sediment was unoiled but of smaller grain size, both species selected the preferred sediment. Red king crabs avoided sediments containing 500-800 mg per g total hydrocarbons if unoiled sediment of the same or larger grain size was available. Addition of oil to the unpreferred sediment increased selection of preferred sediment. In contrast, the Tanner crabs selected fine-grained sediments whether oil was present or not. The lack of avoidance by crabs at concentrations <500 mg per g may lead to long-term exposure to contaminated sediment in areas where benthic sediments are chronically polluted.

Item details