Uwe Krumme | Thünen Institut (original) (raw)

Papers by Uwe Krumme

Research paper thumbnail of Tidal migration and patterns in feeding of the four-eyed fish Anableps anableps L. in a north Brazilian mangrove

Journal of Fish Biology, 2007

The tidal migration, temporal and spatial patterns in feeding of the surface-swimming four-eyed f... more The tidal migration, temporal and spatial patterns in feeding of the surface-swimming four-eyed fish Anableps anableps (Anablepidae) were studied in a macrotidal mangrove area in north Brazil to exemplify the ecology of a tropical intertidal fish. Visual censuses in the main channel showed that abundances were high at low water (LW) and low at high water (HW). Anableps anableps entered the intertidal creeks with the first flood rise. They fed in the inundated mangrove at HW and returned gradually after the ebb current maximum to concentrate again in the subtidal parts of the main channel at LW. This pattern occurred at neap, mid and spring tides throughout the year. The tidal migration was triggered by water level, not by time. In the study area the diet of A. anableps caught with block nets was dominated by intertidal red algae (Catanella sp.). Other important food items were Insecta and Grapsidae. The combination of high inundation and daylight (spring tide-day) provided the best foraging conditions, probably emphasizing the importance of the above-water eye. Darkness and low inundation was linked to poorest foraging conditions (neap tide-night). The quantity of food consumed by A. anableps was clearly influenced by the factors tide, time of day and creek location, but not by size and sex. The qualitative composition of the diet was not influenced by any of the factors, except for mud, which was only ingested at neap tides. The temporal and spatial variability in food consumption suggests that food web modelling in macrotidal areas may lead to misinterpretations of the overall systems dynamics if the spring and neap tide alternation and the diurnal cycle are not considered.

Research paper thumbnail of Diel and Tidal Movements by Fish and Decapods Linking Tropical Coastal Ecosystems

Short-term movements of fishes and decapods can lead to regular changes in biomass, diversity, mo... more Short-term movements of fishes and decapods can lead to regular changes in biomass, diversity, mortality, predation, and flux of energy between adjacent ecosystems. At low latitudes the day-night cycle is relatively stable and uniformly affects activity rhythms of marine organism at all longitudes. In contrast, tidal ranges and tidal types differ significantly between coasts and regions. On coasts with weak tides, twilight migrations connect adjacent habitats. On tidal coasts, migrations are tightly coupled to the interactive effect of the diel and tidal cycles which results in complex but predictable patterns of change within and between ecosystems. Diel and tidal migrations share several similarities (connection of resting and feeding sites, sequence of species and size groups, site fidelity, homing, constant pathways). The spring-neap tide cycle and its interaction with the diel cycle is a key factor influencing regular short-term variations on tidal coasts. The home range of a species on a macrotidal coast may be an order of magnitude greater than that of conspecifics from a microtidal coast, suggesting a need for larger marine parks on macrotidal coasts. Regional comparisons, e.g., between the Caribbean and the Indo-West Pacific, often disregard the significant tidal differences inherent to the ecosystems. It is suggested here that broad-scale comparisons must be redefined; regional comparisons should focus on geographical regions with similar tidal regimes, or on systems with different tidal regimes but with similar species communities.

Research paper thumbnail of A floating device for stationary hydroacoustic sampling in shallow waters

Research paper thumbnail of Dynamics in Mangrove Fish Assemblages on a Macrotidal Coast

We review our studies on the influence of different temporal and spatial scales on changes in ass... more We review our studies on the influence of different temporal and spatial scales on changes in assemblage composition and patterns in feeding of fishes from a macrotidal mangrove estuary in north Brazil. The usefulness of different net types, hydro-acoustics, and visual censuses for scientific sampling in macrotidal mangrove estuaries is discussed. General differences in species richness, biomass and density between estuarine habitats were related to the shoreline gradient and the tidal stage. The major pulses of short-term dynamics in fish movements, changes in transient assemblage compositions and patterns in feeding were the tidal cycle, time of high water, and the spring/neap tide cycle. A comparison of the tide-to-tide, weekly, fortnightly and monthly variation between consecutive samples of abundance, catch weight, and species richness showed that the lowest variation in these parameters occurred among samples taken at spring tides. Recommendations for sampling strategies of long-term monitoring studies and for future research are given.

Research paper thumbnail of Observations of fish migration in a macrotidal mangrove channel in Northern Brazil using a 200kHz split-beam sonar

Aquatic Living Resources, 2003

Research paper thumbnail of Tidal and diel changes in the structure of a nekton assemblage in small intertidal mangrove creeks in northern Brazil

Aquatic Living Resources, 2004

Research paper thumbnail of Contribution to the feeding ecology of the predatory wingfin anchovy Pterengraulis atherinoides (L.) in north Brazilian mangrove creeks

Journal of Applied Ichthyology, 2005

Stomach contents were examined from 136 Amazonian wingfin anchovy, Pterengraulis atherinoides (En... more Stomach contents were examined from 136 Amazonian wingfin anchovy, Pterengraulis atherinoides (Engraulidae), caught from intertidal mangrove creeks at diurnal neap tides between June and September 1997 (early dry season) near Bragança (northern Brazil). The study found that P. atherinoides are specialized predators of juvenile Natantia and Teleostei (mean: 67 and 28% by dry weight, respectively). On average, 5.2 g ha−1 day−1 of Natantia and 2.6 g ha−1 day−1 of Teleostei (wet weight) were eaten by P. atherinoides. Diet changed with fish size as well as by month. While smaller sizes still fed on several food items (e.g. the copepod Pseudiaptomus marshii, the brachyuran crab Pachygrapsus gracilis, amphipods), fish >13 cm standard length (SL) fed exclusively on Natantia and Teleostei. Copepods were especially abundant in July and August, dominating the diet of fish <9 cm SL in numbers (92%). Our results suggest a positive relationship between predator size and prey size, both in penaeid and piscine prey. However, the largest predator size class apparently selected fewer but larger Teleostei prey. More than 64% of Natantia were juvenile penaeid shrimps of commercial importance (Fenneropenaeus subtilis, F. schmitti, Xiphopenaeus kroyeri). Comparison with ichthyoplankton samples taken simultaneously showed that Sciaenidae and Mugilidae were positively selected while Gobiidae and Engraulidae were negatively selected. The presence of pranzia larvae in the stomachs of fish <10 cm SL, from July onward, suggests that these sizes fulfil a mutually beneficial ‘cleaning’ function on other fish. Block net sampling at neap tides showed that P. atherinoides were present in intertidal mangrove creeks throughout the submergence period, suggesting temporal optimization of the foraging time in the eulittoral.

Research paper thumbnail of Spring-neap cycle as a major driver of temporal variations in feeding of intertidal fishes: Evidence from the sea catfish Sciades herzbergii (Ariidae) of equatorial west Atlantic mangrove creeks

Journal of Experimental Marine Biology and Ecology, 2008

Research paper thumbnail of Contribution to the feeding ecology of the banded puffer fish Colomesus psittacus (Tetraodontidae) in north Brazilian mangrove creeks

Brazilian Journal of Biology, 2007

Stomach contents were examined from 102 banded puffer, Colomesus psittacus (Tetraodontidae), caug... more Stomach contents were examined from 102 banded puffer, Colomesus psittacus (Tetraodontidae), caught from intertidal mangrove creeks at diurnal neap tides between June and September, 1997 (early dry season) near Bragança (north Brazil). The study found that C. psittacus were specialized predators of Cirripedia (Balanus spp.) and Brachyuran crabs (Uca spp., Pachygrapsus gracilis) (mean: 58 and 38% by dry weight, respectively), emphasizing a short food chain in the mangrove system. Cirripedia and Brachyura dominated the diet in all size classes, however, the prey spectrum narrowed with fish size. The mean daily consumption of Cirripedia and Brachyura was 6.2% body weight of C. psittacus. On average C. psittacus consumed 100.3 g.ha-1.d-1 of Cirripedia and 178.7 g.ha-1.d-1 of Brachyura (wet weight). The predation on Brachyuran crabs – a significant driver of fluxes of organic matter and energy in the system – provides C. psittacus with an important ecological function in the mangrove food web. A plant-animal interaction is proposed where C. psittacus exerts a mutually beneficial cleaning function on the Aufwuchs (Cirripedia and associated epibiota) of Rhizophora mangle stilt roots. Our results and those of other studies suggest that C. psittacus encounter optimum foraging conditions in the mangrove at high inundations at daylight (spring tide-day) whereas darkness and low inundations are linked to poor foraging conditions (neap tide-night). The C. psittacus resource could be used as an alternative income in the region in terms of i) sustainable catch and filet processing for exports to East Asia, ii) developing certified aquaculture methods for breeding puffers for the aquarium trade.

Research paper thumbnail of Tidal migration and patterns in feeding of the four-eyed fish Anableps anableps L. in a north Brazilian mangrove

Journal of Fish Biology, 2007

The tidal migration, temporal and spatial patterns in feeding of the surface-swimming four-eyed f... more The tidal migration, temporal and spatial patterns in feeding of the surface-swimming four-eyed fish Anableps anableps (Anablepidae) were studied in a macrotidal mangrove area in north Brazil to exemplify the ecology of a tropical intertidal fish. Visual censuses in the main channel showed that abundances were high at low water (LW) and low at high water (HW). Anableps anableps entered the intertidal creeks with the first flood rise. They fed in the inundated mangrove at HW and returned gradually after the ebb current maximum to concentrate again in the subtidal parts of the main channel at LW. This pattern occurred at neap, mid and spring tides throughout the year. The tidal migration was triggered by water level, not by time. In the study area the diet of A. anableps caught with block nets was dominated by intertidal red algae (Catanella sp.). Other important food items were Insecta and Grapsidae. The combination of high inundation and daylight (spring tide-day) provided the best foraging conditions, probably emphasizing the importance of the above-water eye. Darkness and low inundation was linked to poorest foraging conditions (neap tide-night). The quantity of food consumed by A. anableps was clearly influenced by the factors tide, time of day and creek location, but not by size and sex. The qualitative composition of the diet was not influenced by any of the factors, except for mud, which was only ingested at neap tides. The temporal and spatial variability in food consumption suggests that food web modelling in macrotidal areas may lead to misinterpretations of the overall systems dynamics if the spring and neap tide alternation and the diurnal cycle are not considered.

Research paper thumbnail of Diel and Tidal Movements by Fish and Decapods Linking Tropical Coastal Ecosystems

Short-term movements of fishes and decapods can lead to regular changes in biomass, diversity, mo... more Short-term movements of fishes and decapods can lead to regular changes in biomass, diversity, mortality, predation, and flux of energy between adjacent ecosystems. At low latitudes the day-night cycle is relatively stable and uniformly affects activity rhythms of marine organism at all longitudes. In contrast, tidal ranges and tidal types differ significantly between coasts and regions. On coasts with weak tides, twilight migrations connect adjacent habitats. On tidal coasts, migrations are tightly coupled to the interactive effect of the diel and tidal cycles which results in complex but predictable patterns of change within and between ecosystems. Diel and tidal migrations share several similarities (connection of resting and feeding sites, sequence of species and size groups, site fidelity, homing, constant pathways). The spring-neap tide cycle and its interaction with the diel cycle is a key factor influencing regular short-term variations on tidal coasts. The home range of a species on a macrotidal coast may be an order of magnitude greater than that of conspecifics from a microtidal coast, suggesting a need for larger marine parks on macrotidal coasts. Regional comparisons, e.g., between the Caribbean and the Indo-West Pacific, often disregard the significant tidal differences inherent to the ecosystems. It is suggested here that broad-scale comparisons must be redefined; regional comparisons should focus on geographical regions with similar tidal regimes, or on systems with different tidal regimes but with similar species communities.

Research paper thumbnail of A floating device for stationary hydroacoustic sampling in shallow waters

Research paper thumbnail of Dynamics in Mangrove Fish Assemblages on a Macrotidal Coast

We review our studies on the influence of different temporal and spatial scales on changes in ass... more We review our studies on the influence of different temporal and spatial scales on changes in assemblage composition and patterns in feeding of fishes from a macrotidal mangrove estuary in north Brazil. The usefulness of different net types, hydro-acoustics, and visual censuses for scientific sampling in macrotidal mangrove estuaries is discussed. General differences in species richness, biomass and density between estuarine habitats were related to the shoreline gradient and the tidal stage. The major pulses of short-term dynamics in fish movements, changes in transient assemblage compositions and patterns in feeding were the tidal cycle, time of high water, and the spring/neap tide cycle. A comparison of the tide-to-tide, weekly, fortnightly and monthly variation between consecutive samples of abundance, catch weight, and species richness showed that the lowest variation in these parameters occurred among samples taken at spring tides. Recommendations for sampling strategies of long-term monitoring studies and for future research are given.

Research paper thumbnail of Observations of fish migration in a macrotidal mangrove channel in Northern Brazil using a 200kHz split-beam sonar

Aquatic Living Resources, 2003

Research paper thumbnail of Tidal and diel changes in the structure of a nekton assemblage in small intertidal mangrove creeks in northern Brazil

Aquatic Living Resources, 2004

Research paper thumbnail of Contribution to the feeding ecology of the predatory wingfin anchovy Pterengraulis atherinoides (L.) in north Brazilian mangrove creeks

Journal of Applied Ichthyology, 2005

Stomach contents were examined from 136 Amazonian wingfin anchovy, Pterengraulis atherinoides (En... more Stomach contents were examined from 136 Amazonian wingfin anchovy, Pterengraulis atherinoides (Engraulidae), caught from intertidal mangrove creeks at diurnal neap tides between June and September 1997 (early dry season) near Bragança (northern Brazil). The study found that P. atherinoides are specialized predators of juvenile Natantia and Teleostei (mean: 67 and 28% by dry weight, respectively). On average, 5.2 g ha−1 day−1 of Natantia and 2.6 g ha−1 day−1 of Teleostei (wet weight) were eaten by P. atherinoides. Diet changed with fish size as well as by month. While smaller sizes still fed on several food items (e.g. the copepod Pseudiaptomus marshii, the brachyuran crab Pachygrapsus gracilis, amphipods), fish >13 cm standard length (SL) fed exclusively on Natantia and Teleostei. Copepods were especially abundant in July and August, dominating the diet of fish <9 cm SL in numbers (92%). Our results suggest a positive relationship between predator size and prey size, both in penaeid and piscine prey. However, the largest predator size class apparently selected fewer but larger Teleostei prey. More than 64% of Natantia were juvenile penaeid shrimps of commercial importance (Fenneropenaeus subtilis, F. schmitti, Xiphopenaeus kroyeri). Comparison with ichthyoplankton samples taken simultaneously showed that Sciaenidae and Mugilidae were positively selected while Gobiidae and Engraulidae were negatively selected. The presence of pranzia larvae in the stomachs of fish <10 cm SL, from July onward, suggests that these sizes fulfil a mutually beneficial ‘cleaning’ function on other fish. Block net sampling at neap tides showed that P. atherinoides were present in intertidal mangrove creeks throughout the submergence period, suggesting temporal optimization of the foraging time in the eulittoral.

Research paper thumbnail of Spring-neap cycle as a major driver of temporal variations in feeding of intertidal fishes: Evidence from the sea catfish Sciades herzbergii (Ariidae) of equatorial west Atlantic mangrove creeks

Journal of Experimental Marine Biology and Ecology, 2008

Research paper thumbnail of Contribution to the feeding ecology of the banded puffer fish Colomesus psittacus (Tetraodontidae) in north Brazilian mangrove creeks

Brazilian Journal of Biology, 2007

Stomach contents were examined from 102 banded puffer, Colomesus psittacus (Tetraodontidae), caug... more Stomach contents were examined from 102 banded puffer, Colomesus psittacus (Tetraodontidae), caught from intertidal mangrove creeks at diurnal neap tides between June and September, 1997 (early dry season) near Bragança (north Brazil). The study found that C. psittacus were specialized predators of Cirripedia (Balanus spp.) and Brachyuran crabs (Uca spp., Pachygrapsus gracilis) (mean: 58 and 38% by dry weight, respectively), emphasizing a short food chain in the mangrove system. Cirripedia and Brachyura dominated the diet in all size classes, however, the prey spectrum narrowed with fish size. The mean daily consumption of Cirripedia and Brachyura was 6.2% body weight of C. psittacus. On average C. psittacus consumed 100.3 g.ha-1.d-1 of Cirripedia and 178.7 g.ha-1.d-1 of Brachyura (wet weight). The predation on Brachyuran crabs – a significant driver of fluxes of organic matter and energy in the system – provides C. psittacus with an important ecological function in the mangrove food web. A plant-animal interaction is proposed where C. psittacus exerts a mutually beneficial cleaning function on the Aufwuchs (Cirripedia and associated epibiota) of Rhizophora mangle stilt roots. Our results and those of other studies suggest that C. psittacus encounter optimum foraging conditions in the mangrove at high inundations at daylight (spring tide-day) whereas darkness and low inundations are linked to poor foraging conditions (neap tide-night). The C. psittacus resource could be used as an alternative income in the region in terms of i) sustainable catch and filet processing for exports to East Asia, ii) developing certified aquaculture methods for breeding puffers for the aquarium trade.