Re: Heat shock in sea slugs

March 28, 2000
From: Cynthia D. Trowbridge

Dear Roni and Bill,

Hi. Our lab group (Menge/Lubchenco) has been looking at environmental stress, including heat stress, on intertidal species for many years. Some people have looked at heat shock proteins; others have looked at RNA:DNA ratios in mussels, whelks, littorines, etc.; still others have taken ecological approaches. There is a theoretical paper on the ecological consequences of stress in terms of interspecific interactions (competition, herbivory, etc.):

Bruce Menge & Annette Olson (1990) in Trends of Ecology and Evolution (sorry, I can't recall the title).

In terms of opisthobranchs, I have a paper on desiccation stress and how it affects ascoglossan-algal interactions (Placida dendritica in Oregon & New Zealand plus Elysia viridis in Scotland):
•Trowbridge, C.D. (1998) Stenophagous, herbivorous sea slugs attack desiccation-prone, green algal hosts (Codium spp.): Indirect evidence of prey-stress models (PSMs)? J. Exp. Mar. Biol. Ecol. 230: 31-53.

It is one of the first demonstrations that desiccation-stressed seaweeds are more vulnerable to herbivore attack than unstressed conspecifics. Although the mechanism is common in terrestrial systems, there are few recorded cases for marine systems.

In terms of the nudibranch you ask about, [Hermissenda crassicornis] in Oregon it is common intertidally during daytime low tides on emergent substrata. During the summer, we generally have periodic upwelling so animals are not highly stressed during low tides. On days (and even summers) when upwelling does not occur frequently, the intertidal zone really gets damaged by desiccation stress. Whether it is due to heat stress, high light stress, water-loss stress, or some combination of the three remains to be understood.

Stress can compromise chemical and structural defenses of species. As Bill said, I am not clear why you are asking about how stress would affect predation by conspecifics. If you were asking how stress affects fish and crab predation on nudibranchs or affects interspecific competition among slugs for food resources, I would consider those excellent ecological questions. Anyway, good luck with your project.

Cordially,

Cynthia

trowbric@ucs.orst.edu

Trowbridge, C., 2000 (Mar 28) Re: Heat shock in sea slugs. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/2166

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