The macrofauna and macroflora associated withLaminaria digitata andL. hyperborea at the island of Helgoland (German Bight, North Sea)

Schultze, Kirstin; Janke, Klaus; Krüß, Andreas; Weidemann, Wolfgang

doi:10.1007/bf02365430

Cited by 73 publications

(72 citation statements)

References 25 publications

(29 reference statements)

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“…The Laminaria hyperborea biotope supports diverse and abundant invertebrate communities. The invertebrate fauna supported by NE Atlantic kelps is dominated by crustaceans and molluscs (Christie et al, 2003;Moore, 1972;Schultze et al, 1990). Invertebrate abundance is particularly high in the kelp holdfasts and associated with epiphytes on the stipes (Norderhaug et al, 2002).…”

Section: Kelp and Red Seaweeds (Moderate Energy Infralittoral Rock) (mentioning

confidence: 99%

Assessment of goods and services, vulnerability, and conservation status of European seabed biotopes: a stepping stone towards ecosystem-based marine spatial management

et al. 2012

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The goal of ecosystem-based marine spatial management is to maintain marine ecosystems in a healthy, productive and resilient condition; hence, they can sustainably provide the needed goods and services for human welfare. However, the increasing pressures upon the marine realm threaten marine ecosystems, especially seabed biotopes, and thus a well-planned approach of managing use of marine space is essential to achieve sustainability. The relative value of seabed biotopes, evaluated on the basis of goods and services, is an important starting point for the spatial management of marine areas. Herein, 56 types of European seabed biotopes and their related goods, services, sensitivity issues, and conservation status were compiled, the latter referring to management and protection tools which currently apply for these biotopes at European or international level. Fishing activities, especially by benthic trawls, and marine pollution are the main threats to European seabed biotopes. Increased seawater turbidity, dredged sediment disposal, coastal constructions, biological invasions, mining, extraction of raw materials, shipping-related activities, tourism, hydrocarbon exploration, and even some practices of scientific research, also exert substantial pressure. Although some first steps have been taken to protect the European sea beds through international agreements and European and national legislation, a finer scale of classification and assessment of marine biotopes is considered crucial in shaping sound priorities and management guidelines towards the effective conservation and sustainability of European marine resources.

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Section: Kelp and Red Seaweeds (Moderate Energy Infralittoral Rock) (mentioning

confidence: 99%

Assessment of goods and services, vulnerability, and conservation status of European seabed biotopes: a stepping stone towards ecosystem-based marine spatial management

et al. 2012

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“…Besides kelp (L. hyperborea), key components (functional groups) of the kelp forest are: epiphytic algae and fauna attached to the kelp stipes, mobile invertebrates, and fish. Mature kelp stipes are heavily over-grown by epiphytes, mainly red algae (Whittick 1983;Marstein 1997) and sessile animals (Schultze et al 1990;. Large densities of mobile invertebrates, dominated by crustaceans and gastropods, are associated with the kelp (Norderhaug et al 2002;Christie et al 2003).…”

Section: System Stability and Shifts Between Kelp Forests And Sea Urcmentioning

confidence: 99%

Sea urchin grazing and kelp re-vegetation in the NE Atlantic

Norderhaug

Christie

2009

Marine Biology Research

125

114

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Small-scale grazing events where sea urchins have grazed kelp forests to barren grounds have been reported all along the NE Atlantic coast. One large-scale event has been reported where kelp forests along the Norwegian and Russian coast were grazed by sea urchins during the early 1970s. The barren ground area has persisted since. Different theories to explain the grazing event have been presented. This paper seeks to sort and summarize earlier published papers and national reports and to critically examine the most important theories presented to explain the grazing event. The conclusion is that the reason for the event is unknown and it is too late to find causes 40 years after it took place. However, new data and new geographical analysis tools provide insight into the extent and consequences of this dramatic event, and show re-vegetation of kelp forests in the southernmost area. Emphasis in future studies should be given to understand the reasons for shifts between the two ecosystem states and take advantage of the ongoing shift. Such basic ecological knowledge could provide an important basis for better understanding the system and further, to understand the extent to which other observed largescale changes (e.g. climatic changes, fish stock reductions) affect kelp forestÁsea urchin interaction.

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“…Important grazers responsible for changing these systems include sea urchins (Lawrence, 1975;Dayton, 1985;Harrold and Pearce, 1987;Elner and Vadas, 1990), periwinkles (Lein, 1984) and limpets (Hawkins et al, 1992). Also, mobile crustacean macroinvertebrate grazers (amphipods and isopods) are often abundant components of the macrophytic habitat (Hagerman, 1966;Moore, 1972Moore, , 1973Duffy, 1990;Schultze et al, 1990;Christie et al, 1998;Pavia et al, 1999). However, the influence of these crustaceans on the algal community has been reported merely as structural change rather than destructive grazing (see Karez et al, 2000;Worm et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Mechanisms regulating amphipod population density within macroalgal communities with low predator impact

Christie¹,

Kraufvelin²

2004

Sci. Mar.

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SUMMARY: In eight mesocosms (land based basins) macroalgae communities with associated fauna were transplanted from the sea and established during two years. Then, different doses of nutrients (N and P) were added to the basins throughout the following three years. During the period of nutrient addition, macroinvertebrate grazers showed seasonal fluctuations with densities usually between 500,000 and 1 million individuals per mesocosm during summer and to a level of about 100,000 during winter. The macroinvertebrate grazers mainly consisted of about 10 species of amphipods and isopods, among which the amphipod Gammarus locusta dominated strongly by biomass. Although the number of predators was very low, the grazer populations never reached a density where considerable grazing impact could be found on the macroalgae. No increase in grazer density was found in the basins with improved nutrient conditions. Thus food quality may be insufficient for further population growth, or density dependant regulation mechanisms may have prevented the grazers from flourishing and overgrazing the system. In aquarium experiments we showed that G. locusta could grow and reproduce on Fucus serratus, Ulva lactuca, periphyton and detritus, and that cannibalism by adult G. locusta on juveniles may have great impact on the population growth. The basins were run with a water flow through system. Nets were placed in front of the inflow and outflow tubes to measure immigration and emigration. Only few individuals (and no Gammarus sp.) were recorded in the inflowing water, while high numbers of both amphipods and isopods were found in the outflowing water. Emigration reached peak values during night-time, and it was then two to three times as high as during day-time. Emigration of mobile grazers from the basins amounted to 1-2% of the standing stock daily. These mechanisms that regulate grazers do contribute to maintenance of the seaweed dominance and thus the stability of the seaweed community.Key words: Mesocosm, macroalgae, grazers, Gammarus locusta, population regulation, eutrophication. RESUMEN: MECANISMOS QUE REGULAN LA DENSIDAD DE POBLACIONES DE ANFÍPODOS EN COMUNIDADES DE MACROALGAS CONBAJO IMPACTO DE DEPREDACIÓN. -En ocho mesocosmos (depósitos situados en tierra) se trasplantaron comunidades de macroalgas con fauna asociada procedentes del mar y se establecieron durante dos años. Posteriormente se añadieron diferentes dosis de nutrientes (N y P) a los depósitos a lo largo de los tres años siguientes. Durante el período de adición de nutrientes, los macroinvertebrados herbívoros mostraron fluctuaciones estacionales con densidades que por lo general se encontraban entre 500.000 y 1 millón de individuos por mesocosmos durante el verano y hasta un nivel de unos 100.000 ind. en invierno. Los macroinvertebrados herbívoros eran principalmente unas 10 especies de anfípodos e isópodos, entre los cuales el anfípodo Gammarus locusta dominaba mucho por la biomasa. Aunque el número de depredadores fue muy bajo, las poblaciones de herbívoros no...

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The macrofauna and macroflora associated withLaminaria digitata andL. hyperborea at the island of Helgoland (German Bight, North Sea)

Cited by 73 publications

References 25 publications

Assessment of goods and services, vulnerability, and conservation status of European seabed biotopes: a stepping stone towards ecosystem-based marine spatial management

Assessment of goods and services, vulnerability, and conservation status of European seabed biotopes: a stepping stone towards ecosystem-based marine spatial management

Sea urchin grazing and kelp re-vegetation in the NE Atlantic

Mechanisms regulating amphipod population density within macroalgal communities with low predator impact

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