Feeding the fish -a Celtic perspective Feeding the fish -a Celtic perspective Changing potentials for land-sea exchanges of organic matter and other materials in selected Scottish sea lochs

Abstract Much of the coast of the Scottish Highlands is steep and rocky with very limited exchanges between land and sea but the abundant sea lochs provide a dynamic link between the two. Experimental work over the past ten years has shown that salt marshes can play a key role in linking a range of terrestrial and marine communities with up to 40% of their primary productivity being exported. Recently this work has been extended to selected sites in Lochaber and Skye. Comparative studies are in progress to compare the ecosystem dynamics in lochs with varying proportions of salt marsh and contrasting hydrodynamics. The sea lochs of the Western Highlands vary greatly in the relative size of the freshwater catchment, the proportion of intertidal and the mean depth at low water as well as the proportion of salt marsh. In contrast to southern salt marshes the sediment supply is often very limited and generally has a higher proportion of coarser particles. The high rainfall and humidity of the area facilitates the accumulation of organic matter in salt marsh soils. Together these factors have created areas of a unique habitat with a limited distribution along the coast of the Western Highlands, areas which nevertheless play an important role in linking terrestrial and marine communities. Increasing rates of sea level rise, as a result of global warming, are likely to overtake rates of isostatic adjustment and augment existing anthropogenic threats to these special areas. All the five marshes studied showed extensive high marsh and transition communities but rather restricted lower marsh and pioneer communities compared with those of salt marshes elsewhere. Nevertheless the productivity of these salt marsh plant communities and their vertical range in the marsh zonation are comparable. In more exposed areas, however, salt spray can result in the occurrence of salt marsh vegetation well above the levels normally expected. Preliminary results from flux studies at Loch Beag in Skye indicate that the system is particularly dynamic with very variable rates of exchange of organic matter and sediment. It would appear that sediment accretion rates are generally low compared with those in active marsh systems elsewhere. The overall situation is further complicated by the high degree of variation in the inputs and organic loading of fresh water inflow to the system. It seem likely, however, that invertebrate and fish communities in these lochs benefit significantly from the input of organic matter of terrestrial origin and that these intertidal plant communities themselves benefit from material of marine origin. The studies are continuing. 1 Feeding the fish -a Celtic perspective Gearrchuntas 'S ann anns na Gaidhealtachd na h-Alba a tha mòr-chuid na h-oirthire gu math càs agus creagach agus tha na cothroman airson a' bhuinne-sruth rud beag cuingichte ach tha moran lochan-mara ann a' cruthaicheadh an co-cheangal beathachadh eadar talamh 's cuan. 'S e cocheangal beathachadh fiùghantach a tha ann. Air feadh na h-oirthire tha mi a' faicinn, tha mi a' sgrudadh lusan de gach seòrsa anns na làthach-shaillte agus tha mis air rianachd ghoireasan a sgrudadh. Tha mi a' toirt tuairmse na buidseat bhliadhnail mu dheidhinn sruthan eadar tir 's muir. 'S e co-cheangal anabarrach cudromach a tha ann gu dearbh agus 's e ionad-coinnich eadar uisge 's sàile a tha innte cuideachd. O chionn goirid tha mise a' sgrùdadh coig lochan-mara ann an Lochabar agus anns an t-Eilean Sgitheanach. Tha mi a' rannsachadh an àrainneachd anns na lathach-shaillte, gu sònraichte, am prìomh-toradh de lusan agus an t-eòlas-mara anns na coig lochan. 'S e gu math eadardhealaichte a tha na lochan seo. 'S e meud an locha mòra no beaga a tha ann. 'S e na lathach-shaillte fharsaingeachd no cuingichte a tha ann. Agus 's e na lochan domhainn no eudomhainn a tha ann cuideachd. 'S e grùid gu math nas gainmheala a tha ann, bho aite gu aite co-dhiù. Chan eil e uiread grùid anns an uisge-mara nas motha. 'S e àrainneachd gu math sònraichte a tha ann gu deimhinn. Tha e co-cheangal beathachadh eadar talamh 's cuan cuideachd. 'S e an galar de dhearmaid agus neo-shuim a tha a' bagradh oirthir nan Gàidhealtachd. 'S e blàthachadh na cruinne leis a' còmhnard-mara nas airde agus buaidhean na daoine a tha a milleadh an oighreachd beò sin. Tha na lusan a fàs anns an làthach-shaillte, aig cinn nan loch ann an Lochabar agus anns an tEilean Sgitheanach, gu math coltach ris iad sin anns na lathachan-shaillte eile. Tha am prìomh-toradh nan lus co-ionnan gu leor cuideachd. Tha mi air tuairmse a thoirt seachad air a' bhuidseat bliadhnail airson sruthan de stuth fàs-bheairteach agus beathachadhmèinnearachd mu thimcheall am bhuinne-sruth eadar tir agus muir airson Loch Beag ri taobh Loch Bràcadail anns an t-Eilean Sgitheanach. 'S e an àrainneachd gu math eadar dhealaichte 's atharrachail a tha ann. Bho àm gu àm bithidh tuiltean uisge ann, leis eabar agus stuth fàs-bheairteach, agus, aig amannan eile, bithidh tuiltean sàile ann leis stuth-mara de gach seòrsa. Tha creideamh agam gu bheil na h-èisg, agus na beathaicean gun chnaimh-droma anns an loch, a' biathadh leis an stuth seargte bho am prìomh-toradh nan lus anns an làthach-shaillte eadar seòl-mara. 'S e caran cudromach airson iasg a' chuain fhèin a tha ann cuideachd, tha m a' smaoineacheadh. Bithidh mise a' deanamh moran rannsachaidh mu dheidhinn an gnothaich seo. 2 Feeding the fish -a Celtic perspectiv

Managed realignment: recreating intertidal habitats on formerly reclaimed land

Rising sea levels and changes in global and regional weather patterns, coupled with the high cost of maintaining coastal defences, have led coastal managers to look for more cost effective and sustainable methods of flood protection. Managed realignment, the landward adjustment of coastal defences and subsequent tidal inundation of the intervening land has, since the early 1990’s, been increasingly used to fulfil these requirements through out north-west Europe. We focus on managed realignment in north-west Europe specifically because the rationale, implementation and outcomes can differ from intertidal recreation efforts else where. Managed realignment allows tidal ingress through a simple breach in a flood embankment, re-introducing tidal inundation to formerly enclosed land, often for the first time in centuries. Results to date have shown that this technique of coastal management can quickly produce intertidal mudflats which are colonised by invertebrates and, given the appropriate elevation, saltmarsh plants. The method has the twin benefits of reducing sea defence maintenance costs and recreating intertidal habitats lost else where to land claim and erosion, a statuary requirement under European environmental law. A high level of public consultation, and the acquisition of appropriate consents, can mean that it can take several years from conception before a managed realignment scheme is realised. In addition, there are a complex set of socio-economic and environmental variables that can influence the success of a managed realignment scheme. Recreating intertidal habitats by managed realignment is an emerging science in north-west Europe and the eventual outcomes are still uncertain. Despite this, managed realignment makes good sense, allowing the coastline to respond to environmental change in a more natural, sustainable way

Threshold size for flowering in different habitats: Effects of size-dependent growth and survival

For organisms with indeterminate growth, life history theory predicts that in environments where organisms experience high survival rates or gain fecundity with age or size, natural selection favors delayed maturity. In semelparous perennial plants the onset of reproduction is regulated by a threshold size for flowering. We tested this prediction by comparing sand dune populations of the facultative biennial herb Cynoglossum officinale. We collected data on flowering probability, survival, and growth rate in relation to plant size in two habitat types, open areas and poplar thickets, in Meijendel, The Netherlands, and in Holkham, England. Survival of established rosettes was highest in Holkham and lowest in open areas in Meijendel. Relative growth rates in Holkham were about three times as high as those in Meijendel. These findings agreed with the differences in threshold sizes found among the sites: the Holkham field population harbored higher threshold sizes than the Meijendel sites. We used the field data to compare optimal threshold sizes for flowering predicted by three existing models. All three models gave the same rank order for threshold sizes as found in the field: Meijendel open < Meijendel poplar thicket < Holkham. One model, which maximized population growth rate λ, predicted optimal threshold sizes that agreed very well with threshold sizes found in the field. The predictions of the two other models, both maximizing R0, were consistently lower than the threshold sizes observed in Meijendel, while their predictions for Holkham were too high

UvA-DARE (Digital Academic Repository) THRESHOLD SIZE FOR FLOWERING IN DIFFERENT HABITATS: EFFECTS OF SIZE-DEPENDENT GROWTH AND SURVIVAL

Threshold size for lowering in different habitats: effects of size-dependant growth and survival Wesselingh, R.A.; de Jong, T.J.; Klinkhamer, P.G.L.; Boorman, L.A. Published in: Ecology DOI: 10. 1890/0012-9658(1997) General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Abstract. For organisms with indeterminate growth, life history theory predicts that in environments where organisms experience high survival rates or gain fecundity with age or size, natural selection favors delayed maturity. In semelparous perennial plants the onset of reproduction is regulated by a threshold size for flowering. We tested this prediction by comparing sand dune populations of the facultative biennial herb Cynoglossum officinale. We collected data on flowering probability, survival, and growth rate in relation to plant size in two habitat types, open areas and poplar thickets, in Meijendel, The Netherlands, and in Holkham, England. Survival of established rosettes was highest in Holkham and lowest in open areas in Meijendel. Relative growth rates in Holkham were about three times as high as those in Meijendel. These findings agreed with the differences in threshold sizes found among the sites: the Holkham field population harbored higher threshold sizes than the Meijendel sites. We used the field data to compare optimal threshold sizes for flowering predicted by three existing models. All three models gave the same rank order for threshold sizes as found in the field: Meijendel open Ͻ Meijendel poplar thicket Ͻ Holkham. One model, which maximized population growth rate , predicted optimal threshold sizes that agreed very well with threshold sizes found in the field. The predictions of the two other models, both maximizing R 0 , were consistently lower than the threshold sizes observed in Meijendel, while their predictions for Holkham were too high