Importance of suspended particulate organic matter in the diet of Nephrops norvegicus (Linnaeus, 1758)

Cesar Augusto Da Silva Santana,Anne Marie Power,Alina M Wieczorek,Patricia Browne,Conor T Graham

doi:10.1038/s41598-020-60367-x

Cesar Augusto Da Silva Santana, Anne Marie Power + Show 3 more

Open Access

https://doi.org/10.1038/s41598-020-60367-x

Copy DOI

Abstract

The extent to which commercially important Nephrops norvegicus lobsters feed on particulates in the wild is unknown, even though this could be an important way for burrow-dwelling females to avoid starvation during the long breeding season. This was investigated using δ13C and δ15N isotopic signatures in tissues with long and short turnover rates to provide diet discrimination and compare this between males and females. Secondary objectives examined size-related differences and calculated the trophic position based on the new results. Almost half the diet (47%) was made up of suspended particulate organic matter (POMsusp) alone. Fish was another important item in the diet, with plankton and invertebrate sources coming much lower down in dietary importance. Significantly more suspension feeding was observed in small or medium sized individuals than large ones in both sexes. However, there were no sex-related patterns, despite females being restricted to burrows for part of the analysis period. Female diet was almost identical to males and POMsusp comprised a large component of the diet in both sexes. The trophic position was estimated at 2.94 ± 0.16 (mean ± SD), which was at the lower end of the range reported in previous studies (2.60 to 4.32).

Highlights

Dublin Bay prawn, Nephrops norvegicus, is a decapod crustacean and an important economic resource in Europe: global production of this fishery was 59,033 tons in 2016 of which the United Kingdom and Republic of Ireland were the main producers, capturing up to 32,708 and 10,379 tons per annum respectively during 2012–20161
Since suspended food in the form of plankton biomass is seasonally lower during the Winter female burrow-dwelling period[21,22], we propose that females instead feed on suspended particulate organic matter (POM) (i.e. POMsusp)
The SIMMR model output showed that POMsusp and fish were the main food sources for all consumer groups and time periods in the analysis

Summary

Introduction

Dublin Bay prawn, Nephrops norvegicus, is a decapod crustacean and an important economic resource in Europe: global production of this fishery was 59,033 tons in 2016 of which the United Kingdom and Republic of Ireland were the main producers, capturing up to 32,708 and 10,379 tons per annum respectively during 2012–20161. Restriction to burrows for most of the year is evidenced by a lower percentage of females in fisheries catches during the breeding season, which is elongated in Irish and Scottish grounds over Autumn, Winter and early Spring[17]. SIA can more fully represent POMsusp and soft-bodied prey items in the diet as well as providing a time-integrated view of feeding compared with a ‘snapshot’ provided by stomach contents analysis[25]. In the present study, 13C and 15N isotopic signatures in long and short-term storage tissues were used to compare signals in Nephrops’ diet between males and females, both in the period when females were in burrows during the lead-up to spawning and the period after females had spawned and were actively feeding, maturing new gonads and mating.

Objectives

Methods

Results

Conclusion