Histological intersex (ovotestis) in the European lobster Homarus gammarus and a commentary on its potential mechanistic basis

Abstract

This paper provides the first report of the intersex (ovotestis) condition in the European lobster Homarus gammarus. A single specimen (10% of males sampled) presenting the condition was discovered as part of routine sampling, from the Weymouth Bay region of the English Channel, UK. The lobster presented externally as a male, but upon histological examination was seen to contain an ovotestis, containing elements of both male and female gonadal tissue. Previtellogenic oocytes were present in several otherwise normal seminiferous tubules throughout the testis. The seminiferous tubules were also engaged in the production of apparently normal sperm lineages, and mature spermatozoa were present within the tubule lumens. In some cases, oocytes were in direct contact with mature spermatozoa within the same seminiferous tubules. The significance of this finding is placed into context with a previous observation of elevated intersexuality in the congeneric species H. americanus collected from specific sites in Canadian waters. The potential mechanism for development of intersex in lobsters, which is probably related to a disrupted signalling to the germinal component of the testis from the decapod androgenic gland, may be an effect of exposure to endocrine disrupting chemicals in the marine environment.KEY WORDS: Crustacean · Decapoda · Androgenic gland · Endocrine disruption · Commercial fishery Resale or republication not permitted without written consent of the publisherContribution to DAO Special 6 'Disease effects on lobster fisheries, ecology, and culture'

Vitellogenin is not an appropriate biomarker of feminisation in a Crustacean

“…Although the relationship between oestrogenic chemicals and crustacean feminisation is still uncertain, other (non-oestrogenic) chemicals in the environment may cause unambiguous crustacean feminisation. Indeed, chemical contaminants (or mixtures of contaminants) have been implicated as a cause of the intersex phenotypes observed in multiple crustacean groups (Moore and Stevenson, 1994;Jungmann et al, 2004;Ayaki et al, 2005;Short et al 2012a;Stentiford, 2012). However, the finding that obviously female sexual characteristics can appear on males in the absence of any Vtg expression suggests that the aberrant expression of Vtg in males is not suitable as an 'early warning' biomarker, even if there are chemicals that unambiguously feminise crustaceans.…”

Ecotoxicological Risk of Endocrine Disruptors

“…Although some parasite-induced intersexuality exists naturally, several authors have shown that crustacean intersexuality was linked to environmental contamination in copepods (Moore and Stevenson, 1991), amphipods (Barbeau and Grecian, 2003;Jungmann et al, 2004;Ford et al, 2006;Yang et al, 2008;Hyne, 2011;Short et al, 2012), and decapods (Sangalang and Jones, 1997;Ayaki et al, 2005;Stentiford, 2012). A proportion of intersexes may be indirectly caused by anthropogenic contamination, as contaminant-exposed crustaceans present significant increases in infection by microsporidia (Short et al, 2014).…”

A Crab Is Not a Fish: Unique Aspects of the Crustacean Endocrine System and Considerations for Endocrine Toxicology

“…In any case, no prominent example of endocrine disruption, comparable to imposex in prosobranch gastropods, is known for crustaceans. Examples of intersex that appear to be related to pollution have been reported for different crustacean species (14)(15)(16)(17)(18)(19). But no cause-effect relationships have been established.…”