Morphological change over time in the deep-sea holothurian Psychropotes longicauda.
Supervisors: Jennifer Durden, Tammy Horton (NOC, Southampton)
Climate change refers to long term shifts in temperature and associated weather patterns has pronounced effect on all realms of the ocean including deep seas. These responses include shifts in community composition, adaptations, or even morphological changes over time period. During mid-1990s in the Porcupine Abyssal Plain Sustained Observatory (PAP-SO), NE Atlantic, there has been a huge increase in density and biomass of deep-sea fauna, especially with decrease in body length in holothurians, referred as ‘Amperima event’. This shifts in abundance along with decrease in length was assumed to be in relation with change in food supply from upper ocean, associated with long term climate events. However, during the event over all morphological variation on holothurians was not addressed. Psychropotes longicauda a deep-sea cucumber is one of the most studied holothurians from PAP-SO, has been known to show cryptic species diversity. It has a distinctive long “tail” consisting major portion of its biomass, with considerable variation in tail morphology. Since this species presents high individual variation till today there is lack of proper taxonomic description on this species from different locality along with many species described under this genus synonymized as P. longicauda. Hene this study gives a detailed quantification on body and tail morphology in P. longicauda from PAP-SO in addition to morphological variation over time in P. longicauda in relation to sea surface temperature variability observed over North Atlantic Ocean; AMO. This study finds morphological variation over time in P. longicauda for different phases of AMO, with long and wider species during cool AMO and short and less wide species during warm AMO however, with no variability on tube feet and dorsal papillae. This is assumed to be in relation with changes in food supply from upper ocean. The primary energy source for deep sea fauna is the detrital flux (organic matter) from surface ocean hence any variations in sea surface temperature patterns associated with climate variability could result shifts in abundance and community composition of phytoplankton and other associated communities causing changes in the quality and quantity of available food for benthic fauna. With high alerts on current status of global warming resulting in increased ocean temperature, along with decreased detrital flux in deep ocean expected in future oceans, my results demonstrate how the members of deep-sea fauna, especially holothurians are likely to respond to changes in food supply from surface ocean over time in relation with temperature variability. Since not many studies have been conducted in morphological variations on deep-sea fauna, I expect this study to be a starting point for more advanced studies in relation to morphological variations in deep-sea fauna.