First reported cases of intersex (ovotestis) in the flatfish species dab Limanda limanda: Dogger Bank, North Sea

Abstract

This paper provides the first report of the intersex (ovotestis) condition in the flatfish species dab Limanda limanda. Specimens presenting the condition were collected from the North Dogger Bank in the North Sea during the United Kingdom National Marine Monitoring Programme in 2003. Two of the individuals collected (14.3% of the males sampled) presented externally as males but upon histological examination were seen to contain both male and female gonadal tissues. Previtellogenic oocytes were suspended within a matrix of spermatogonia and spermatocytes. One of the specimens also presented dilated testicular follicles filled with masses of mature spermatozoa. The significance of this finding in the United Kingdom's sentinel offshore monitoring species is discussed with relation to potential offshore effects of exposure to endocrine disrupting chemicals (EDCs). KEY WORDS: Flatfish · Endocrine disruption · Limanda limanda · Ovotestis · Ovary · Testis · Reproduction Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 301: [307][308][309][310] 2005 EDCs extend beyond inland river systems to coastal waters. With the exception of the reports of plasma vitellogenin and ovotestis in male Mediterranean swordfish Xiphias gladius (Fossi et al. 2001 and De Metrio et al. 2003, respectively), little evidence has so far been presented on endocrine disruption in the offshore environment.This study provides the first report of intersex in the United Kingdom National Marine Monitoring Programme's (NMMP) offshore sentinel flatfish species dab Limanda limanda. Two fish presenting the condition were present in a sample of 50 dab collected from the Dogger Bank, an NMMP sampling station in the central North Sea, during 2003. This discovery marks the first histologically confirmed case of intersex in a marine fish species collected from an offshore site. MATERIALS AND METHODSDab Limanda limanda were captured using 30 min tows of a standard Granton trawl on the Northern Dogger Bank, North Sea (55°03' 53'' N, 02°04' 26'' E), as part of the NMMP, in July 2003. The sex, size (total length) and presence of external signs of disease were recorded for 50 fish using methodology specified by the International Council for the Exploration of the Sea (ICES) (Bucke et al. 1996). Following external disease assessment, fish were sacrificed by a blow to the head, followed immediately by severing of the spinal chord. Samples of liver, kidney, spleen and gonad were fixed in neutral buffered formalin for 24 h followed by transfer to industrial methylated spirit. Fixed samples were processed to wax in a vacuum infiltration processor using standard protocols. Sections were cut at 3 to 5 µm on a rotary microtome and resulting tissue sections were mounted onto glass slides before staining with haematoxylin and eosin (H & E). Stained sections were analysed by light microscopy (Eclipse E800, Nikon) and digital images of histological features were obtained using the Lucia™ Screen Measurement System (Nik...

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“…In many cases, the condition has been linked to the ambient presence of chemicals known to disrupt normal hormonal functioning of the host (Stentiford & Feist, 2005). Similar reports in other mullet species such as flathead grey mullet, as much as 21% of intersex was registered from the polluted environment Bay of Biscay and Northern Spain (Puy-Azurmendi et al, 2013;Bizarroa et al, 2014).…”

Effect of age on liver pathology and other diseases in flatfish: implications for assessment of marine ecological health status

“…In light of data presented in the present study, it will now be important to consider the relationship between elevated liver cancer prevalence and potential causal factors at offshore sites. Studies demonstrating potential offshore endocrine disruption effects in populations of dab from the Dogger Bank region of the North Sea (Stentiford & Feist 2005, Scott et al 2007) and the recent finding of over-expression of vitellogenin mRNA in liver tumours of dab (Small et al 2010) are provocative directors for further research investigating the relationship between liver-cancer formation and the endocrine system of marine fish and their elevated association with particular geographic locations (Stentiford et al 2009). …”

Evidence for estrogenic endocrine disruption in an offshore flatfish, the dab (Limanda limanda L.)

“…Although, two intersex dab were found in the Dogger Bank area during the CSEMP survey in 2003 (Stentiford & Feist, 2005), none was found in the 2004 and 2005 surveys. This rarity of intersex in dab could be taken as evidence that the small amount of estrogen to which they are apparently being exposed is not detrimental to the health of individuals or populations.…”