Long-term fluctuations in intertidal communities in an Irish sea-lough: Limpet-fucoid cycles

2017 ◽  
Vol 196 ◽  
pp. 70-82 ◽  
Author(s):  
Colin Little ◽  
Cynthia D. Trowbridge ◽  
Graham M. Pilling ◽  
Penny Stirling ◽  
David Morritt ◽  
...  
Author(s):  
Julia D Sigwart ◽  
Mathieu Lundy ◽  
Jamie T A Dick ◽  
Carola Becker

Abstract Data on the demography and reproduction of marine species provide important information for a sustainable fisheries management. We show that the size at onset of maturity in female Nephrops norvegicus has been in decline for over 20 years and has always been above the established minimum landing size (MLS) in the Western Irish Sea. Determining the size at onset of maturity is one important factor to inform an effective MLS, such that individuals can reproduce at least once. The length at which half of females are sexually mature (L50) in the overall population declined by over 12% in two decades, from 23.6 mm in 1997 to 20.6 mm in 2016, while the MLS has remained at 20 mm. While L50 values differ among permanent sampling stations, the decline was observed at all stations. Current practice thus allows immature females to be landed before they reproduce and contribute to recruitment. While it is not always possible to identify the determining factors that drive the decline in SOM, we argue that it is appropriate to recognize this as an indicator of declining system productivity.


2018 ◽  
Vol 210 ◽  
pp. 142-152 ◽  
Author(s):  
Colin Little ◽  
Cynthia D. Trowbridge ◽  
Graham M. Pilling ◽  
Dylan M. Cottrell ◽  
Caitlin Q. Plowman ◽  
...  
Keyword(s):  

2014 ◽  
Vol 64 (8) ◽  
pp. 1163-1180 ◽  
Author(s):  
Sarah Gallagher ◽  
Roxana Tiron ◽  
Frédéric Dias
Keyword(s):  

A two-dimensional numerical model is formulated to simulate long-term mixing in the coastal waters over the European Continental Shelf. By using both tidal and wind-driven components, the mean circulation over this region is computed and is shown to be in good agreement with earlier estimates from (i) modelling studies, (ii) observations of residual flow, and (iii) observations of mean sea level distribution. Long-term gradients of sea level in the adjacent oceanic region are found to be unimportant for shelf circulation. These residual flow components are used to develop a mixing model, observational data of the mixing of 137 Cs (released from Windscale over a 17 year period) are used to calibrate and evaluate the model. The model accurately simulates the transport routes of this material both spatially and temporally. This transport is shown to be dependent on both advection and dispersion. The model is used to determine various time constants for the shelf seas, namely: age, residence times and turn-over-times. Thus, the turn-over-time of the North Sea is calculated to be 530 d compared with a value of 328 d for the Irish Sea. The geographical distribution of turn-over-times differentiates regions of vigorous mixing from more stagnant regions and thereby indicates regions conducive to the formation of thermal fronts. The model also indicates that about one third of the material discharged from Windscale is lost to the ocean in the vicinity of the shelf edge to the north and west of Scotland.


Author(s):  
C. Melissa Miner ◽  
Jennifer L. Burnaford ◽  
Karah Ammann ◽  
Benjamin H. Becker ◽  
Steven C. Fradkin ◽  
...  

1986 ◽  
Vol 1 (20) ◽  
pp. 11
Author(s):  
M.C. Deo ◽  
R. Burrows

Potential inconsistencies in the predictions of long term wave heights can be experienced as a result of different methods of analysis possible when using directional wave data. This paper attempts to illustrate some of them. It involves analysis of two sets of directional wave data - one froa a coastal location in the Irish Sea and another from an offshore location in the North Sea. An attempt is made to eliminate the discrepancies between the long term return-value wave height predictions based upon the conditional height distributions associa ted with different direction sectors and those derived from the oonl-directional data set.


Oikos ◽  
2020 ◽  
Vol 129 (11) ◽  
pp. 1645-1656
Author(s):  
Diana E. LaScala‐Gruenewald ◽  
Mark W. Denny

2011 ◽  
Vol 11 (6) ◽  
pp. 1641-1656 ◽  
Author(s):  
L. S. Esteves ◽  
J. J. Williams ◽  
J. M. Brown

Abstract. Although storminess is often cited as a driver of long-term coastal erosion, a lack of suitable datasets has only allowed objective assessment of this claim in a handful of case studies. This reduces our ability to understand and predict how the coastline may respond to an increase in "storminess" as suggested by global and regional climate models. With focus on 16 km of the Sefton coastline bordering the eastern Irish Sea (UK), this paper analyses available measured datasets of water level, surge level, wave height, wind speed and barometric pressure with the objective of finding trends in metocean climate that are consistent with predictions. The paper then examines rates of change in shoreline position over the period 1894 to 2005 with the aim of establishing relationships with climatic variability using a range of measured and modelled metocean parameters (with time spans varying from two to eight decades). With the exception of the mean monthly wind speed, available metocean data do not indicate any statistically significant changes outside seasonal and decadal cycles. No clear relationship was found between changes in metocean conditions and rates of shoreline change along the Sefton coast. High interannual variability and the lack of long-term measurements make unambiguous correlations between climate change and shoreline evolution problematic. However, comparison between the North Atlantic Oscillation winter index (NAOw) and coastline changes suggest increased erosion at times of decreasing NAOw values and reduced erosion at times of increasing NAOw values. Erosion tends to be more pronounced when decreasing NAOw values lead to a strong negative NAO phase. At present, anthropogenic changes in the local sediment budget and the short-term impact of extreme events are still the largest threat likely to affect coastal flooding and erosion risk in the short- and medium-term. Nevertheless, the potential impacts of climate change in the long-term should not be ignored.


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