Detrimental effects of Ulva lactuca (L.) exudates and low oxygen on estuarine crab larvae

Johnson, Donna A.; Welsh, Barbara L.

doi:10.1016/0022-0981(85)90043-7

Cited by 66 publications

(34 citation statements)

References 24 publications

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“…ii is pussible that this alga can provide refuge for older juvenile shore crabs under more natural conditions. Exudates of U. lactuca in com'bination with low oxygen levels (<25 % O2 saturation) can cause high mortality of first stage blue crab zoea larvae (Johnson & Welsh 1985). The present study showed no support for such detrimental effects on first instar shore crab from any of the investigated algal species (0 to 5 O/u control mortality), even though we measured oxygen levels below 25 % saturation at night.…”

Section: Ephemeral Algae As Nursery Habitatscontrasting

confidence: 77%

Predation on postlarvae and juveniles of the shore crab Carcinus maenas:importance of shelter, size and cannibalism

Moksnes¹,

Pihl²,

Montfrans³

1998

Mar. Ecol. Prog. Ser.

183

128

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Settlement and early juvenile stages are considered a bottleneck in the life history of many epibenthic organisms because of high predation mortality. Nursery habitats may play an irnportant role in mitigating settlement and post-settlement mortality by providing refuge from predation. We examined these relationships in postlarvae and early juvenile stages of the shore crab Carcinus maenas L. in laboratory and field tethering experiments. We studied habitat and size related habitat mortality using postlarvae and young juvenile crabs as prey, and various predators, including juvenile conspecifics, in several habltats common in shallow (0 to 1 m) soft bottom nursery areas on the Swedish west coast. Settling mortality was high in open sand (80 to go%), whereas a significant habitat refuge was obtained in mussel beds, eelgrass and filamentous green algae, the latter yielding the lowest mortality (13 to 14%). Small differences in structural complexity of ephemeral macroalgae dramatically affected predation mortality of tirst instar crabs, with a slgniiicant refuge obtaineci oriiy irl diyde of medium complexity. Predation rate on tethered crabs in the field was high (52 to 67 X) only on the smallest crabs (

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Section: Ephemeral Algae As Nursery Habitatscontrasting
confidence: 77%

Predation on postlarvae and juveniles of the shore crab Carcinus maenas:importance of shelter, size and cannibalism
Moksnes¹,
Pihl²,
Montfrans³
1998
Mar. Ecol. Prog. Ser.
183
5
128
1
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~~show abstract~~

“…P. elegans is also more tolerant of high temperatures, especially in combination with extreme salinities and low oxygen concentrations (Berglund 1980, Berglund & Bengtsson 1981. It is there fore likely that the observed shift in dominance between the 2 species is due to increased water temperatures since the mid-1980s and occurrence of filamentous algae in the Zostera meadows, which causes nocturnal hypoxia when respiration exceeds photo synthesis (Johnson & Welsh 1985, Amund 2009.…”

Section: Discussionmentioning
confidence: 99%

Shift in seagrass food web structure over decades is linked to overfishing
Baden¹,
Emanuelsson²,
Pihl³
et al. 2012
Mar. Ecol. Prog. Ser.
114
7
129
2
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Empirical field studies in seagrass have revealed that overgrowth by filamentous algae which reduces seagrass growth can be explained by a top-down cascading effect caused by declines in top predators, which is enforced by eutrophication. On the Swedish west coast, 60% of the seagrass has disappeared since the 1980s. We hypothesised that overfishing, responsible for a > 90% decline in the cod stock, and the 4 to 8 times increase in nutrient load since the 1930s have altered the seagrass structure and function during recent decades. We used quantitative samples from the 1980s and 2000s and analysed the trends in abundance of the 4 feeding guilds: top predatory fish, intermediate predatory fish, crustacean omnivores and mesoherbivores. Since the 1980s, the commercial catch of gadoids on the Swedish west coast has decreased by > 90%, and here we found that the biomass of top predators (gadoids and trout) that forage in seagrass has decreased by approximately 80%. In contrast, the biomass of intermediate predatory fish (gobids and sticklebacks) has increased 8 times during summer and 11 times during autumn, while mesoherbivores (idoteids and gammarids > 7 mm) have more or less disappeared from the seagrass bed. We thus found clear evidence that a shift in seagrass food web structure has taken place over the last 3 decades. Combining these findings with our recent empirical results from field cage experiments in the Skagerrak seagrass, where we manipulate top-down and bottom-up regulation, we conclude that lack of grazers in concert with eutrophication most likely contributed to the overgrowth by filamentous algae and disappearance of the seagrass on the Swedish west coast. KEY WORDS: Food web structure · Overfishing · Eutrophication · SeagrassResale or republication not permitted without written consent of the publisher

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“…As illustrated by Norkko & Bonsdorff (1996), the response to the combinations of hypoxia, hydrogen sulfide and the physical presence of the algal mat induces a more rapid response than mere hypoxia, illustrating the importance of physical cover and possibly toxic exudates from the algae (Johnson & Welsh 1985, Aneer 1987. Everett (1994) argued that the presence of hydrogen sulfide and its toxicity (Theede et al 1969) is the mam factor inducing infa.una1 escape responses and mortality.…”

Section: Discussionmentioning
confidence: 99%

Rapid zoobenthic community responses to accumulations of drifting algae
Norkko¹,
Bonsdorff²
1996
Mar. Ecol. Prog. Ser.
204
7
130
2
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In the northern Baltic Sea, occurrences of benthic drifting macroalgal mats have become an ~ncreasing problem. Accumulations of algae induce hypoxia and anoxia in zoobenthos above the halocline on shallow sandy bottoms. The immediate and temporal responses of a macrozoobenthic community to accumulat~ons of drifting algal mats were studied in a field experiment on an exposed shallow sandy bottom (7.5 m depth) in the northern Baltic Sea. Experimental algal plots (50 X 50 cm) corresponding to amounts recorded in the field (440 g dwt m-') were enclosed in net-bags and attached to the bottom. Changes in zoobenthic community structure under the algae were compared with ambient control plots for a period of 5 wk with sampling every seventh day. Community parameters (species, abundance and biomass) in the control community remained stable. Structural differences were recorded after 9 d, and community breakdown after 16 to 21 d of algal cover. Only opportunists and species tolerant to hypoxia remained under the algae. High particulate organic C/N ratios in the sediment under algal plots were recorded after 4 wk, indicating deposition of organic material from the algae to the sediment. Init~al recovery 15 d ) after termmated algal stress was rapid and dominated by a mass invasion ot hydrobud snatls, poss~bly attracted by enl-~chment of the sediment. Laboratory tests on algal degradation showed a 10-fold increase In phosphorus In the water due to nutrient leakdye during hypoxia (20'% Oz). Algal cover, and the ~nduction of hypoxla through degradation of the algae, exhibited severe effects on zoobenthlc community structure and a potential to accelerate local eutrophication. We therefore [eel that the escalating amounts of drifting algae recorded in the f~e l d are a significant threat to the coastal biota.

~~show abstract~~

Detrimental effects of Ulva lactuca (L.) exudates and low oxygen on estuarine crab larvae

Cited by 66 publications

References 24 publications

Predation on postlarvae and juveniles of the shore crab Carcinus maenas:importance of shelter, size and cannibalism

Predation on postlarvae and juveniles of the shore crab Carcinus maenas:importance of shelter, size and cannibalism

Shift in seagrass food web structure over decades is linked to overfishing

Rapid zoobenthic community responses to accumulations of drifting algae

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