Intersexuality in aquatic invertebrates: Prevalence and causes.
This review is the first assembling information on intersexuality in aquatic invertebrates, from freshwater to estuarine and marine environments. Intersex is a condition whereby an individual of a gonochorist (separate sexes) species has oocytes or distinct stages of spermatogonia, at varying degrees of development, within the normal gonad of the opposite gender (i.e. spermatocytes in the ovary or oocytes in the testis), often involving alterations in the gonadal structure, reproductive tract or external genitalia. By the end of 2016 we found approximately 340 records of aquatic invertebrate species evidencing signs of intersexuality (or imposex), all comprised within the Phyla Mollusca and Arthropoda. Gastropod molluscs are by far the group with more examples documented (256 species), followed by crustaceans, i.e., decapods, copepods and amphipods. To our knowledge no further cases of intersexuality were known concerning other invertebrate taxa. Despite some reports suggesting that a baseline level of intersexuality may occur naturally in some populations, the causes are multifaceted and mostly linked with environmental contamination by estrogenic and organotin endocrine disrupting chemicals (EDCs), parasitism, and genetic/environmental sex determination abnormalities. A more comprehensive discussion about the origin of intersexuality, prevalence and causes, knowledge gaps and future research directions in the light of new omics scientific advances (genomics, proteomics and transcriptomics) is also provided. The lack of studies linking molecular responses of invertebrate intersex individuals to multiple stressors represents a true challenge to be further investigated in the future.
MARE - Marine and Environmental Sciences Centre, Laboratório Marítimo da Guia, Faculdade de Ciências da Universidade de Lisboa, Av. Nossa Senhora do Cabo 939, 2750-374 Cascais, Portugal. Electronic address: tgrilo@uc.pt.
Tiago F
TF
Grilo
MARE - Marine and Environmental Sciences Centre, Laboratório Marítimo da Guia, Faculdade de Ciências da Universidade de Lisboa, Av. Nossa Senhora do Cabo 939, 2750-374 Cascais, Portugal.
Rui
R
Rosa
D000818:Animals; D059001:Aquatic Organisms / Q000502:physiology; D001181:Arthropods / Q000502:physiology*; D012734:Disorders of Sex Development / Q000662:veterinary*; D052244:Endocrine Disruptors / Q000633:toxicity*; D004787:Environmental Pollution; D005260:Female; D008297:Male; D008974:Mollusca / Q000502:physiology*; D015995:Prevalence
D052244:Endocrine Disruptors
Aquatic invertebrates; Environmental contamination; Feminization; Imposex; Intersexuality; Masculinization